Such a heat exchanger housing with two pot-like (pot-shaped) heat exchanger housings inserted one into the other is known from DE 101 43 479 C1. The fluid flow space enclosed between these is divided by two flow guiding formations arranged at circumferentially spaced locations from one another into two partial flow spaces, so that the fluid being fed via an inlet opening enters one of the partial flow spaces, reaches the area of the fluid flow space formed between the two bottom walls there and can then flow into the second partial flow space and via this to the outlet opening. Axially limited webs are provided in the circumferential direction between the flow guiding formations at the inner heat exchanger housing in the area in which the circumferential walls adjoin the bottom walls of the respective heat exchanger housing, and said webs are pressed to come into contact with web-like heat exchanger projections located opposite in the area in which the circumferential wall of the outer heat exchanger housing adjoins the bottom wall of the outer heat exchanger housing and thus they form a press fit formation, by which the two heat exchanger housings are held rigidly on one another, in the area in which the circumferential walls adjoin the bottom walls. As a result, the two heat exchanger housings are in direct heat transfer contact in the area of these press fit formations, so that the surface of the heat exchanger arrangement that can be efficiently used for the heat transfer can be enlarged.